The hydraulic transport of mineral coal though pipelines, particularly through vertical sections of mine shafts by means of a three-chamber-tube-distributor, has been described in the Journal "Bergbau" 1976, part 12, pages 474 and 475. Such three-chamber-tube-distributors operate in accordance with a cyclic chamber-sluice method in which the tube chambers are in the form of long U-shaped tube loops. The individual tube chambers periodically pass through the three working stages of "filling", "waiting" and "forwarding". The tube chambers are filled with slurry under reduced pressure and are then emptied under high pressure. The filling and emptying of the tube chambers takes place periodically under the influence of a control system so that a quasi-continuous flow of slurry is produced in the transport pipeline. The solids are fluidized in a slurry basin and then pumped as a slurry into the tube chambers by means of a low-pressure filling pump. The chambers are subsequently closed by shut-off slide valves. The slurry is forced out of the tube chambers into a transport pipeline. The above filling and transport procedure is certainly complicated. However, it operates according to a fixed control program and is monitored electronically.
It is also known from the German Auslegeschrift DE-AS No. 24 57 943 that it is possible to transport coal, ores or similar solids over great distances and changes in height hydraulically by means of a three-chamber-tube-distributor and with the addition of only very small amounts of liquid. In this system, on the one hand, the tube chambers act as intermediate boosters and, on the other hand, they act in conjunction with filling and metering equipment as the distributor device.
In this known tube-chamber distributor-system there are constant periods of time for filling and transporting and the control measures are substantially based on the use of timing elements in connection with the pressure measurement instruments and limit switches for the shut-off devices to determine the beginning and the end of a give filling and transporting cycle. Alterations in the pumps, pipelines and instruments caused by abrasive wear-and-tear are compensated for within certain limits by adjustment of the timing elements.
However, any sudden fluctuations in the concentration of the slurry, such as when a mixture of several solids of different densities is being transported, can cause alterations of the filling and transporting time intervals which, because of the rigid timing schedule of the timing elements, cannot be compensated for in the short term.
One consequence of the foregoing is that during the filling cycle of a tube chamber either the available volume of the chamber is not fully exploited or an over-filling of the chamber occurs. In the latter case, there can be serious consequences because solids are able to pass through the chamber into the return-flow or supply sections of the transport liquid pipeline from where they can be deposited, in an undesirable manner, in the shut-off devices. In order to be able to avoid blockages and excessive abrasive wear-and-tear it is necessary to use shut-off devices which are comparable in size to the shut-off devices which regulate the admission and discharge of the slurry into and from the tube chamber. However, for the return-flow and the supply of the transport liquid it would be quite feasible to operate with substantially smaller shut-off devices.
During the transport cycle of the known tube-chamber distributor-system in situations in which the total available volume of the chamber is not fully exploited during the preceding filling cycle there is an undesirable introduction of a considerable volume of transport liquid into the transport pipeline following the expulsion of the slurry from the chamber.
Quite apart from the fact that the volume of transport liquid involved is not available for subsequent re-use, and must therefore be replaced the effective transport capacity for slurry is reduced and therefore the operating costs for the whole installation are unnecessarily increased.
On the other hand, if an over-filling of the available volume of the chamber with slurry occurs during the filling cycle the result is that there is not a complete emptying of the chamber during the successive transport cycle. As a consequence, during the next filling cycle, there is once again an over-filling of the chamber.
The known tube-chamber distributor-systems also operate unsatisfactorily in situations where they are used for the transport of slurry to a movable delivery location. The speed of the transport process alters when the length of the transport pipelines is altered with the result that the cycle times necessary for optimal exploitation of the tube chambers are also altered. Adjustment of the switching operations necessary for optimal exploitation of the tube chambers is not possible in view of the fixed control program.